Conventionally, various electro-optical devices using a light emitting element, such as an organic light emitting diode (hereinafter, referred to as “OLED”) element, have been proposed. The electro-optical devices are generally known to have a configuration in which, for example, scan lines and data lines are wired on a glass substrate and a plurality of pixel circuits are formed to correspond to intersections of the scan lines and the data lines. Further, the pixel circuits are known to be configured to have respective light emitting elements as well as respective driving transistors for enabling a current to flow in the light emitting elements.
In order to meet recent demand for size-reduction and high precision, an electro-optical device using a silicon substrate as a basis for wiring the scan lines and the data lines has been proposed.
Meanwhile, to measure characteristics of the pixel circuits of the conventional electro-optical device, it has been known that with a current source installed in each of a plurality of data lines, a test voltage is applied to a gate terminal of a driving transistor of each pixel circuit connected to the respective data line to allow a current to flow to the respective light emitting element so that luminance emitted by the light emitting element is measured.
As described above, the test of applying the test voltages to the gate terminals of the driving transistors is conventionally performed to measure the characteristics of the pixel circuits of the electro-optical device. However, with recent requirements of miniaturization of the electro-optical device, the driving transistors are increasingly reduced in size, making it difficult to increase withstanding voltages of the driving transistors. Thus, it becomes hard to apply large test voltages to the gates of the driving transistors and the test voltages to be applied to the gate terminals of the driving transistors become smaller. In addition, when the test is performed, it takes time to adjust the test voltages, which vary for each of the plurality of data lines, to be equal among the gate terminals of the driving transistors connected to the data lines, which increases the time for measuring the characteristics of the pixel circuits and leads to an increase in manufacturing cost.